Add and subtract relay

ABSTRACT

An add and subtract relay for a pinball machine or the like having an add solenoid and a subtract solenoid mounted side by side with respective drive pawls and associated ratchet wheels, the teeth of both of the ratchet wheels being faced in the same direction. The wheels are axially detented together with one of them being axially shiftable with respect to the frame for operating a switch when the wheels are rotated out of, and into, a relative reference phase position. As an added feature the wheels have telescoping concentric shafts with cooperating discs at the ends of the shafts with indicia to provide constant indication of offset in terms of the number of steps of phase position. Each solenoid has a return spring so that the drive pawl advances the engaged ratchet wheel forwardly one step upon deenergization of the solenoid. A cam is provided adjacent each drive pawl for crowding the pawl inwardly against the ratchet wheel as it approaches the end of its forward stroke to block the ratchet wheel against unwanted rotation in either direction.

3,793,510 451 Feb. 19, 1974 ADD AND SUBTRACT RELAY AESTRACT 75 Inventor; An add and subtract relay for a pinball machine or the like having an add solenoid and a subtract solenoid mounted side by side with respective drive pawls and associated ratchet wheels, the teeth of both of the Roman F. Garbark, Westchester, Ill. [73] Assignee: D. Gottlieb & Company, Northlake,

lll.

Feb 3 1 73 ratchet wheels being faced in the same direction. The

[21] Appl. No.: 336,488

[22] Filed:

wheels are axially detented together with one of them being axially shiftable with respect to the frame for operating a switch when the wheels are rotated out of,

235/92 EV, 235/92 c, 235/132 E,

5 Clmm" and into, a relative reference phase position. As an 5 92 R 5 /]4() added feature the wheels have telescoping concentric G06m 3/14, G06m 3/02 235/92 C, 92 EV, 132 E;

Int, shafts with cooperating discs at the ends of the shafts [58] Field of se rch, with indicia to provide constant indication of offset in terms of the number of steps of phase position. Each solenoid has a return spring so that the drive pawl advances the engaged ratchet wheel forwardly one step [56] References Cited UNITED STATESPATENTS upon deenergization of the solenoid. A cam is provided adjacent each drive pawl for crowding the pawl inwardly against the ratchet wheel as it approaches the Ernest at al 235/132 E end of its forward stroke to block the ratchet wheel against unwanted rotation in either direction.

2,426,715 9/1947 Tatter.............. 2,551,656 5/1951 Breitensteinn'n. 3,112,067 11/1963 Primary ExaminerPaul J. Henonv 14 Claims, 8 Drawing Figures Assistant ExaminerJoseph M. Thesz, Jr.

Attorney, Agent, or Firm-Wolfe, Hubbard, Leydig, Voit & Osann, Ltd. v

EATENTEDFEB 19 I974 snzei '1 or 2 ADD AND SUBTRACT RELAY It is common in pinball machines for the machine to accept coins in advance, payment for a series of games and to award freegamesto the player when certain objectives are achieved. The coins and free games together provide a total running credit, which credit is gradually exhausted upon the playing of successive games to turn off the machine. It is known in a device of this type to provide an add and subtract relay to establish. a running credinwith each game that is played subtracting one unit from such credit until the entire credit has been used up. Players are aware that in many machines game credits can be artifically achieved by lifting the machine an inch or two and dropping it to the floor, thereby shock-ing the add portion of the relay. i'nto advancement.

It is. an object of the present invention to provide an add and subtract relay for a pinball machine or the like which is inherently shockproof and in which a shock applied in any direction is self-cancelling and. incapable of producing any net movement of either the add or subtract portions of the relay. More specifically, it is an object of the present invention to, provide an add and subtract relay having solenoids which are arranged side 7 by side and having ratchet wheels upon which the teeth are faced in the same direction so that a shock has an equalized effect upon the ratchet wheels thereby precluding any net movement of one wheel with respect to the other.

It is another object of the present invention to provide an add and subtract relay having coaxial ratchet wheels terminating in concentric shafts, with one of the shafts displaying indicia and the other shaft having an indicator for indicating, in terms of number of steps, the degree of offset in phase position between the two ratchet wheels, thereby to provide a constant indication, or tally, of the game credit, that is, the number of games which may be played, without increase in credit, before the machine turns itself off.

It is still another object of the present invention to provide an add and subtract relay which is not only selfcancelling in the face of applied shock but in which the drive pawls are normally cammedinto a blocking position with respect to their ratchet wheels, thereby to positively block the ratchet wheels against rotation in either direction during intervals between application of successive energizing pulses to the solenoids.

It is a more detailed object to provide an add and subtract relay in which stops are provided between con centric ratchet wheels to adjustably limit the degree of offset in phase position between the two wheels.

Other objects and advantages of the invention will become apparent upon reading the attached detailed description and upon reference to the drawings in which:

FIG. 1 is a face view of an add and subtract relay constructed in accordance with the invention.

FIG. 2 is a sectional view of the relay of FIG. 1 looking along the line 2--2 therein.

FIG. 3 is a fragmentary left-hand view of the relay of FIG. 1 as viewed along the line 33.

FIG. 4 is a transverse section looking along the line 4-4 in FIG. 2.

FIG. 5 is an underside view of the relay shown in FIG. I.

FIG. 6. is a fragmentary view similar to FIG 3, but showing the relative shifting movement between, the ratchet wheelsfor actuating a switch.

FIG. 7 isa fragmentary section looking along the line 77 of FIG. 2 and showing rotational stop surfaces between the two adjacent ratchet wheels.

FIG. 8 is a fragmentary perspective showing one of the drive pawls.

While the invention has been described in connection with a preferred embodiment, it will be understood that I do not intend to limit the invention to this particular embodiment but intend, on the contrary, to cover the various alternative and equivalent forms of the invention included within the spirit and scope of the appended claims.

Turning now to the drawings an addand subtract relay constructed in accordance with the invention is indicated at 10. The frame, which is of boxy shape, is formed of a back plate 11 having an integral end plate 12 providing a bearing 13. Secured to the plate 1 l is a second end plate 14 providing a bearing 15, the plates ll, 14 being secured together by one or more machine screws 16. The plate 11 is bent inwardly at 18 to provide a solenoid mounting ledge and additionally bent inwardly at 19 to provide a surface for mounting keeper pawls which will be referred to in due course. For mounting the relay to supporting structure a mounting bracket 19 is provided which may, if desired, be spot welded to the plate 11. I

Arranged side by side on the plate 11 are add and subtract solenoid assemblies indicated at 21, 22 respectively. Taking the solenoid assembly 21 by way of example, it is seated upon the ledge 18 and the magnetic circuit is completed via an auxiliary pole piece 23 which is secured to the plate 11 by means of machine screws 24. The assembly 21 has the usual hollow cylindrical winding 25 in which a core or armature 26. is freely telescoped. Pivoted to the end of the armature by a pivot 27 is a drive pawl 28. Encircling the armature, and pressing against the drive pawl is a return spring 29.

Generally alined with the drive pawl 28 is a ratchet wheel 30 which is preferably of molded construction having an integral shaft 31, a web 32 and a rim 33 which presents a set of ratchet teeth 34. Cooperating with the ratchet teeth 34 is a keeper pawl 35 in the form of a U-shaped piece of spring Wire secured by a clamp 36 and machine screw 37 to the flange l8.

Returning to the details of the drive pawl 28 as shown in FIG. 8, it includes a central blade-like portion 40 having laterally extending shoulders 41 42 which present a sharp front edge 43. For the purpose of serv- 7 ing as a limit stop .for the forward or thrusting movement of the drive pawl 28 and for the purpose of can ming the drive pawl against the ratchet wheel toward the end of its thrusting movement, stop fingers 45, 46 (see FIG. 8) are integrally formed in the frame plate 11 (see also FIG. 5). The fingers 45, 46 have a relief space In accordance with one of the important'aspects of the present invention the two ratchet wheels 30, 30s are arranged coaxially and have cooperating axially facing detent surfaces which are biased together, one of the ratchet wheels being journaled for shifting movement to operate a switch when the ratchet wheels move out of, and into, a reference phase position. Thus, referring to FIGS. 2 and 6, the shaft 31 of the ratchet wheel 30 is slidably mounted in bearing 15, and the two ratchet wheels have detent surfaces 50, 50s (FIG. 6) which are biased together by a light coil spring 51. A switch 52 mounted on the plate 14 responds to the endwise shifting movement. When the two ratchet wheels are in a relative reference position, the detent surfaces 50, 50s are nested together and the switch 52 is open. However, upon forward stepping of the solenoid 21 and movement of the ratchet wheel 30 out of the reference position, the detent surfaces cam edgewise upon one another shifting the ratchet wheel 30 endwise against the restoring force of the spring 51 and. closing the switch 52 as shown in FIG. 6.

In operation, assuming that the ratchet wheels are in their nested, detented position shown in FIG. 2, the add solenoid may be stepped forwardly a number of steps with the first step serving to unseat the detented surfaces to throw the switch. Subsequently, when the subtract solenoid assembly is stepped forwardly an equivalent number of steps, the ratchet wheels are restored to their relative in-phase position resulting in seating of the detent and restoration of the-switch contacts to their initial condition.

In accordance with one of the aspects of the present invention the shafts of the two ratchet wheels are extended concentrically and cooperating means are provided at the ends of the shafts for indicating the degree, that is, the number of steps, of offset of the ratchet wheels from their condition of coincidence. More specifically in accordance with the invention, at least one of the concentric shafts is provided with a disc carrying indicia reading directly in the number of steps of offset while the other shaft carries an indicator. Turning to the drawings and particularly to FIGS. 1 and 2, the outer of the two concentric shafts 31s, carries a disc 60 having a row of.indicia 61 while the inner shaft has, mounted upon its end, a disc 62 having an indicator in the form of a viewing window 63. The disc 62 is secured to the inner shaft by a screw 64. When the two ratchet wheels coincide in phase, a zero is viewable through the window 63. As the disc 62 associated with the add solenoid is indexed forwardly, a progressively higher number is exposed. Conversely, stepping of the subtract solenoid, moving the disc 60 in the same direction, progressively reduces the count until it is restored to zero accompanied by operation of the switch.

In accordance with one of the detailed aspects of the present invention the disc 60 carries a double set of indicia, from zero to nine in two cycles, and the disc 62 carries a double set of indicators in the form of viewing windows 63 arranged 180 apart. In addition, rotational stop surfaces are provided between the two ratchet wheels so that relative motion is limited, in the present instance to 180. One stop member may conveniently be in the form of an axially extending screw 70 which is screwed into the web of one of the ratchet wheels and which engages a radially extending stop member 71 integrally formed in the other. Preferably, the web 32 (FIG. 2) may be formed with a circular row of holes of a diameter just slightly less than the screw diameter, and the screw may be forcibly screwed into a selected hole cutting its own shallow thread.

By means of such construction ratchet wheels having 20 teeth may be used to provide up to of offset corresponding to ten steps; in other words, the present add and subtract relay may be used to provide a maximum credit of ten. The double set of indicia and the two indicators enable the user of the machine to read a number which is in generally upright position. Indeed, for viewing purposes, the lower half of the disc 62 may be masked from view so that only the window showing an upright number, and which is in the top half, is viewable at any given time.

While the operation of the device will be apparent from the above description it will be helpful to review a typical operating sequence, assuming the unit to be installed in a pinball machine of a type providing free games as an award for certain scoring objectives. The relay initially occupies the state shown in FIGS. 1 and 2, with the switch 52 turned off and with zero games visible in the viewing window. If it is assumed that three coins are inserted to purchase a total of three games, the coins, by means not shown, impulse the add solenoid 21 three times, indexing the disc 62 so that the number 3 shows through the viewing window. The first of the impulses operates the switch 52 to turn the machine on for the playing of the first game.

At the end of the first game means, not shown, are provided for impulsing the subtract solenoid which indexes the disc 60 in the same direction as the disc 62 one step, so that the number 2" shows through the viewing window indicating two games are yet to be played.

If, during playing of the second game, a scoring objective is achieved sufficient to award the player a free game, the add solenoid is impulsed, by means not shown, indexing the disc 62 forwardly one step and changing the indication from 2 to 3". The add and subtract relay thus provides a continuously indicated running credit of the number of games both paid for and free which may be played on the machine before additional payment is required.

While constant visual indication of credit is one of the advantageous and convenient features of the construction, it will be understood that the relay has utility without the indicator feature and, if desired, the portions of the shafts 31, 31s which project beyond the side plate 12 (FIG. 2) may be omitted from the construction.

As stated above, it is one of the features of the device that it is perfectly reliable and cannot be defeated by shocking or jarring the playing machine in which it is mounted. Since theratchet wheels are mounted side by' side and symmetrically with respect to the ratchet wheels, any applied shock tends to be self-cancelling as far as movement of the ratchet wheels is concerned. This will be shown by considering the effect of a blow from the right, as viewed in FIGS. 1 and 2, which is the most effective direction from which a blow may be applied. Such a blow will, it is true, tend to move the armatures 26,26s against the force of their return springs to theright, i.e., into the solenoids. Provided'theprecaution is taken of using relatively stiff return springs, any blow of reasonable magnitude will displace the armatures less than one toothdistance so that the drive pawls will be promptly restored to initial position without any movement of the ratchet wheels. However, even assuming that a blow is, applied of a magnitude to displace the armatures enough for the ratchets to take a tooth, both of the ratchet wheels will be advanced one unit in the same direction so that the relative positions of the two ratchet wheels, and the number which is viewable at the indicator, will remain unchanged. This removes any possibility that a free game may be obtained by jarring or dropping the machine.

Moreover, it is one of the features, as previously pointed out in connection with FIGS. 4 and 8, that the fingers45, 46 which engage and guide each of the drive pawls, are formed to cam the pawl radially inward to a positive blocking position at the end of the return stroke. This insures that where one of the ratchet wheels is indexed forwardly by action of its solenoid and return spring, there is no possibility that the other ratchet wheel will be disturbed, even though considerable friction might exist, due to failure of lubrication, between the two ratchet wheels. Thus, the present relay may be expected to operate reliably without any need for maintenance or attention over long periods of time, for example the life span'of the playing machine in which the unit is used.

While it is preferred, for reasons of simplicity and economy, to provide detent surfaces 50, 50s directly upon the engaged end surfaces of the ratchet wheels, it will be understood by one skilled in the art that the detent surfaces need not be integral with the ratchet wheels but may be located in a remote position. For example, perfectly flat, non-detented surfaces may, if desired, be provided between the adjacent ratchet wheels, and cooperating detents may, instead, be provided between the discs 60, 62. Where the detent surfaces are of the simple, opposed type interposed between the discs, the change would be accompanied by reversing the direction of the biasing spring 51, for example, by interposing the spring in the space between the two adjacent ratchet wheels. Thus the term having cooperating axially facing detent surfaces, as used herein, is not limited to detent surfaces actually formed on the ratchet wheels.

Also while the add and subtract relay has been described in connection with use in a pinball machine, it will be understood that it is not limited to such usage and that the relay may be employed wherever high reliability and shockproofness is desired in the carrying of a constantly changing credit. it will be understood that while the illustrated deviceemploys a ratchet wheel of 20 teeth to provide a maximum credit of ten units, the

construction is not limited to any particular number of teeth and not limited to any particular placement of stops for limiting the maximum credit which may be carried. Thus, the stop screw 70 may be screwed into any selected hole in the web 32 of Wheel 30 to limit the range of relative movement.

The above discussion has focused primarily on the mechanical aspects of the construction. With regard to the electric connections used in a pinball machine, one set of contacts on the switch 52 are connected in series with the coil of the subtract solenoid 22 so that such solenoid cannot perform a subtraction unless the credit is greater than zero. This means that the reading can never go below zero, that is, only a positive credit can be registered. In any application requiring both positive and negative balances to be shown, this interlocking switch connection is simply not used.

What I claim is:

1. An add and subtract relay for a pinball machine or the like comprising, in combination, a frame, an add solenoid having a drive' pawl and associated ratchet wheel, a subtract solenoid having a drive pawl and associated ratchet wheel, the ratchet wheels being arranged coaxially and having cooperating axially facing detent surfaces biased into engagement, one of the ratchet wheels being axially shiftable with respect to the frame and the detent surfaces being so formed that when the ratchet wheels are in phase the shiftable wheel occupies a reference axial position but when the ratchet wheels are rotationally offset from one another the shiftable wheel occupies a shifted position, and a switch responsive to the shifting movement, the ratchet wheels having teeth faced in the same direction and the solenoids being arranged side by side symmetrically with respect to the ratchet wheels thereby to preclude rotation of one of the ratchet wheels with respect to the other upon application of shock to the relay.

' 2. An add and subtract relay for a pinball machine or the like comprising, in combination, a frame, an add solenoid having a drive pawl and associated ratchet wheel, a subtract solenoid having a drive pawl and associated ratchet wheel, the ratchet wheels being arranged coaxially and coupled to respective axially facing detent surfaces, one of the detent surfaces being axially shiftable with respect to the frame and so coupled to the ratchet wheels that shifting takes place when the ratchet wheels move into and out of phase with one another, a switch responsive to the shifting movement, the ratchet wheels having teeth faced in the same direction and the solenoids being arranged side by side symmetrically with respect to the ratchet wheels thereby to preclude rotation of one of the ratchet wheels with respect to the other upon application of shock to the relay.

3. An add and subtract relay for a pinball machine or the like comprising, in combination, a frame, an add solenoid having a drive pawl and associated ratchet wheel, a subtract solenoid having a drive pawl and associated ratchet wheel, the ratchet wheels being arranged coaxially side by side, means including a switch coupled to the ratchet wheels and so arranged that the circuit is made and broken as the ratchet wheels are indexed into and out of an in-phase condition, the ratchet wheels having teeth faced in the same direction and the solenoids being arranged side by side symmetrically with respect to the ratchet wheels so that a shock applied to the relay has the same effect upon each of the wheels thereby to preserve their relative phase positions, and means coupled to the wheels for providing constant visual indication of the degree the wheels are offset in phase from one another.

4. An add and subtract relay for a pinball machine or the like comprising, in combination, a frame, an add solenoid having a drive pawl and associated ratchet wheel, a subtract solenoid having a drive pawl and associated ratchet wheel, the ratchet wheels being arranged coaxially side by side, means including a switch coupled to the ratchet wheels and so arranged that the circuit is made and broken as the ratchet wheels are indexed into and out of an in-phase condition, the ratchet wheels having teeth faced in the same direction and the solenoids being arranged side by side symmetrically with respect to the ratchet wheels so that a shock applied to the relay has the same effect upon each of the wheels thereby to preserve their relative phase positions, means coupled to the wheels for providing constant visual indication of the degree the wheels are offset in phase from one another, and stops interposed between the ratchet wheels for limiting the maximum amount of offset,

5. The combination as claimed in claim 4 in which one of the ratchet wheels has a circular series of axially facing openings and in which a screw is screwed into a selected one of the openings and in which a radially extending stop surface is provided on the remaining ratchet wheel in the path of movement of the screw.

6. An add and subtract relay for a pinball machine or the like comprising, in combination, a frame, an add solenoid having a drive pawl and'associated ratchet wheel, a subtract solenoid having a drive pawl and associated ratchet wheel, the ratchet wheels being arranged coaxially and having axially facing detent surfaces biased into engagement, one of the ratchet wheels being axially shiftable with respect to the frame and the detent surfaces being so formed that when the ratchet wheels occupy an inphase position the shiftable whee] occupies a reference axial position but when the ratchet wheels are rotationally offset from one another the shiftable wheel occupies a shifted position, a switch responsive to the shifting movement, the ratchet wheels having teeth faced in the same direction and the solenoids being arranged side by side symmetrically with respect to the ratchet wheels so that a shock applied to the relay has the same effect upon each of them thereby to preserve the relative positions of the wheels, and means for providing constant visual indication of the degree of offset. I

7. An add and subtract relay for a pinball machine or the like comprising, in combination, a frame, an add 1 solenoid having a pawl and associated ratchet wheel, a

subtract solenoid having a pawl and associated ratchet wheel, the ratchet wheels being arranged coaxially and having cooperating axially facing detent surfaces biased into engagement, one of the ratchet wheels being actually shiftable with respect to the frame and the detent surfaces being so formed as to produce shifting movement when the wheels are into and out of phase with one another, a switch responsive to the axial shifting movement, the ratchet wheels being faced in the same direction and the solenoids being arranged symmetrically side by side so as to preclude relative rotation of the wheels with respect to one another upon application of shock to the relay, the ratchet wheels having concentric shafts, and indicator means at the ends of the concentric shafts including indicia for directly indicating the phase offset between the ratchet wheels in terms of steps of indexing movement.

8. The combination of claim 7 in which one of the shafts carries a disc having indicia thereon and the other shaft carries an indicator cooperating with the indicia.

9. The combination as claimed in claim 7 in which the shafts have respective cooperating discs at the ends thereof, the disc associated with the outer shaft having a circular row of indicia and the disc associated with the inner shaft having an aperture for viewing the indicia.

10. The combination as claimed in claim 8 in which the disc on the outer shaft has a double set of indicia 8 serially arranged in respective semi-circles and in which the inner shaft has a double set of indicators arranged apart for providing redundant indication of phase position and so that at least one indicator provides generally upright reading of the indicia.

11. The combination as claimed in claim 10 in which the two indicators are in the form of two windows arapssdmlfitl". frgm naqa tt sn,

12. The combination as claimed in claim 7 in which the switch responsive to the axial shifting movement is connected in series with the subtract solenoid to disable the subtract solenoid whenever the wheels are in phase, thereby insuring that only a positive credit is indicated at the indicia. 7 V 7 13. An add and subtract relay for a pinball machine or the like comprising, in combination, a frame, an add solenoid having a drive pawl and associated ratchet wheel, a subtract solenoid having a drive pawl and associated ratchet wheel, the ratchet wheels being arranged coaxially and having cooperating axially facing detent surfaces'biased into engagement, one of the ratchet wheels being axially shiftable with respect to the frame so that when the wheels are relatively indexed in and out of phased condition the shiftable wheel is shifted endwise, a switch responsive to the shifting movement, the teeth on the ratchet wheels being faced in the same direction and the solenoids being located side by side on the same side of the ratchet wheels so that a shock applied from any direction is ineffective to produce. relative rotational movement of the ratchet wheels, each of the ratchet wheels having a keeper pawl, the solenoids each having a return spring and so arranged that when the solenoid is operated the drive pawl thereon takes a tooth of the associated ratchet wheel and so that when the solenoid is deenergized the ratchet wheel is stepped forwardly by the force of the return spring.

14. An add and subtract relay for a pinball machine or the like comprising, in combination, a frame, an add solenoid having a drive pawl and associated ratchet and the detent surfaces being so formed as to produce 4 shifting movement when the ratchet wheels are relatively indexed into and out of the in-phase condition, a switch responsive to the shifting movement, the

ratchet wheels being faced in the same direction and the solenoids being symmetrically located side by side with respect thereto so as to preclude differential rotation of the ratchet wheels in the face of applied shock, the solenoids having return springs so that upon deenergization the drive pawl takes a tooth and so that upon deenergization the drive pawl is thrust forwardly by the spring to advance the associated ratchet wheel, each of the drive pawls having a' stop to limit forward movement and each of the stops having an associated camming surface for camming the drive pawl radially inwardly toward the associated ratchet wheel incident to completion of forward movement for positively blocking the ratchetwheel against rotation in either direction. 

1. An add and subtract relay for a pinball machine or the like comprising, in combination, a frame, an add solenoid having a drive pawl and associated ratchet wheel, a subtract solenoid having a drive pawl and associated ratchet wheel, the ratchet wheels being arranged coaxially and having cooperating axially facing detent surfaces biased into engagement, one of the ratchet wheels being axially shiftable with respect to the frame and the detent surfaces being so formed that when the ratchet wheels are in phase the shiftable wheel occupies a reference axial position but when the ratchet wheels are rotationally offset from one another the shiftable wheel occupies a shifted position, and a switch responsive to the shifting movement, the ratchet wheels having teeth faced in the same direction and the solenoids being arranged side by side symmetrically with respect to the ratchet wheels thereby to preclude rotAtion of one of the ratchet wheels with respect to the other upon application of shock to the relay.
 2. An add and subtract relay for a pinball machine or the like comprising, in combination, a frame, an add solenoid having a drive pawl and associated ratchet wheel, a subtract solenoid having a drive pawl and associated ratchet wheel, the ratchet wheels being arranged coaxially and coupled to respective axially facing detent surfaces, one of the detent surfaces being axially shiftable with respect to the frame and so coupled to the ratchet wheels that shifting takes place when the ratchet wheels move into and out of phase with one another, a switch responsive to the shifting movement, the ratchet wheels having teeth faced in the same direction and the solenoids being arranged side by side symmetrically with respect to the ratchet wheels thereby to preclude rotation of one of the ratchet wheels with respect to the other upon application of shock to the relay.
 3. An add and subtract relay for a pinball machine or the like comprising, in combination, a frame, an add solenoid having a drive pawl and associated ratchet wheel, a subtract solenoid having a drive pawl and associated ratchet wheel, the ratchet wheels being arranged coaxially side by side, means including a switch coupled to the ratchet wheels and so arranged that the circuit is made and broken as the ratchet wheels are indexed into and out of an in-phase condition, the ratchet wheels having teeth faced in the same direction and the solenoids being arranged side by side symmetrically with respect to the ratchet wheels so that a shock applied to the relay has the same effect upon each of the wheels thereby to preserve their relative phase positions, and means coupled to the wheels for providing constant visual indication of the degree the wheels are offset in phase from one another.
 4. An add and subtract relay for a pinball machine or the like comprising, in combination, a frame, an add solenoid having a drive pawl and associated ratchet wheel, a subtract solenoid having a drive pawl and associated ratchet wheel, the ratchet wheels being arranged coaxially side by side, means including a switch coupled to the ratchet wheels and so arranged that the circuit is made and broken as the ratchet wheels are indexed into and out of an in-phase condition, the ratchet wheels having teeth faced in the same direction and the solenoids being arranged side by side symmetrically with respect to the ratchet wheels so that a shock applied to the relay has the same effect upon each of the wheels thereby to preserve their relative phase positions, means coupled to the wheels for providing constant visual indication of the degree the wheels are offset in phase from one another, and stops interposed between the ratchet wheels for limiting the maximum amount of offset.
 5. The combination as claimed in claim 4 in which one of the ratchet wheels has a circular series of axially facing openings and in which a screw is screwed into a selected one of the openings and in which a radially extending stop surface is provided on the remaining ratchet wheel in the path of movement of the screw.
 6. An add and subtract relay for a pinball machine or the like comprising, in combination, a frame, an add solenoid having a drive pawl and associated ratchet wheel, a subtract solenoid having a drive pawl and associated ratchet wheel, the ratchet wheels being arranged coaxially and having axially facing detent surfaces biased into engagement, one of the ratchet wheels being axially shiftable with respect to the frame and the detent surfaces being so formed that when the ratchet wheels occupy an inphase position the shiftable wheel occupies a reference axial position but when the ratchet wheels are rotationally offset from one another the shiftable wheel occupies a shifted position, a switch responsive to the shifting movement, the ratchet wheels having teeth faced in the same direction and the solenoids being arranged side by side symmetRically with respect to the ratchet wheels so that a shock applied to the relay has the same effect upon each of them thereby to preserve the relative positions of the wheels, and means for providing constant visual indication of the degree of offset.
 7. An add and subtract relay for a pinball machine or the like comprising, in combination, a frame, an add solenoid having a pawl and associated ratchet wheel, a subtract solenoid having a pawl and associated ratchet wheel, the ratchet wheels being arranged coaxially and having cooperating axially facing detent surfaces biased into engagement, one of the ratchet wheels being actually shiftable with respect to the frame and the detent surfaces being so formed as to produce shifting movement when the wheels are into and out of phase with one another, a switch responsive to the axial shifting movement, the ratchet wheels being faced in the same direction and the solenoids being arranged symmetrically side by side so as to preclude relative rotation of the wheels with respect to one another upon application of shock to the relay, the ratchet wheels having concentric shafts, and indicator means at the ends of the concentric shafts including indicia for directly indicating the phase offset between the ratchet wheels in terms of steps of indexing movement.
 8. The combination of claim 7 in which one of the shafts carries a disc having indicia thereon and the other shaft carries an indicator cooperating with the indicia.
 9. The combination as claimed in claim 7 in which the shafts have respective cooperating discs at the ends thereof, the disc associated with the outer shaft having a circular row of indicia and the disc associated with the inner shaft having an aperture for viewing the indicia.
 10. The combination as claimed in claim 8 in which the disc on the outer shaft has a double set of indicia serially arranged in respective semi-circles and in which the inner shaft has a double set of indicators arranged 180* apart for providing redundant indication of phase position and so that at least one indicator provides generally upright reading of the indicia.
 11. The combination as claimed in claim 10 in which the two indicators are in the form of two windows arranged 180* from one another.
 12. The combination as claimed in claim 7 in which the switch responsive to the axial shifting movement is connected in series with the subtract solenoid to disable the subtract solenoid whenever the wheels are in phase, thereby insuring that only a positive credit is indicated at the indicia.
 13. An add and subtract relay for a pinball machine or the like comprising, in combination, a frame, an add solenoid having a drive pawl and associated ratchet wheel, a subtract solenoid having a drive pawl and associated ratchet wheel, the ratchet wheels being arranged coaxially and having cooperating axially facing detent surfaces biased into engagement, one of the ratchet wheels being axially shiftable with respect to the frame so that when the wheels are relatively indexed in and out of phased condition the shiftable wheel is shifted endwise, a switch responsive to the shifting movement, the teeth on the ratchet wheels being faced in the same direction and the solenoids being located side by side on the same side of the ratchet wheels so that a shock applied from any direction is ineffective to produce relative rotational movement of the ratchet wheels, each of the ratchet wheels having a keeper pawl, the solenoids each having a return spring and so arranged that when the solenoid is operated the drive pawl thereon takes a tooth of the associated ratchet wheel and so that when the solenoid is deenergized the ratchet wheel is stepped forwardly by the force of the return spring.
 14. An add and subtract relay for a pinball machine or the like comprising, in combination, a frame, an add solenoid having a drive pawl and associated ratchet wheel, a subtract solenoid having a drive pawl and associated ratchet wheel, thE ratchet wheels being arranged coaxially and having cooperating axially facing detent surfaces biased into engagement, one of the ratchet wheels being axially shiftable with respect to the frame and the detent surfaces being so formed as to produce shifting movement when the ratchet wheels are relatively indexed into and out of the in-phase condition, a switch responsive to the shifting movement, the ratchet wheels being faced in the same direction and the solenoids being symmetrically located side by side with respect thereto so as to preclude differential rotation of the ratchet wheels in the face of applied shock, the solenoids having return springs so that upon deenergization the drive pawl takes a tooth and so that upon deenergization the drive pawl is thrust forwardly by the spring to advance the associated ratchet wheel, each of the drive pawls having a stop to limit forward movement and each of the stops having an associated camming surface for camming the drive pawl radially inwardly toward the associated ratchet wheel incident to completion of forward movement for positively blocking the ratchet wheel against rotation in either direction. 